plate tectonics geol 101 lecture 24pages.geo.wvu.edu/~kite/geol101_2006lect24platetectiii.pdf ·...

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Plate Tectonics GEOL 101 Lecture 24

Prop: Test 3 Invitations

The Grand Tetons, WyomingHow Are Mountains Built?

Spread Centers Feed Subduction Zones

Missing Mechanisms for Continental Drift:Sea Floor Spreading & Subduction

Continents are Passive “Boats”

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Subduction Zones: Ocean-Ocean Margin

Subduction Zones: Ocean-Continent Margin

Orogeny Associated with Subduction ZoneSingle Figure with Some Vertical Exaggeration

Plummer et al. 10th ed, Figure 20.6

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Orogeny Associated with Subduction ZoneSingle Figure with More Vertical Exaggeration

Orogeny Associated with Subduction Zone

Cra

ton Fold and Thrust Belt

“Orogeny” Flipped for East Coast View

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Orogeny Associated with Subduction ZoneSingle Figure – Flipped & Tilted to Match Eastern US

Younger Sed Rx

Sea Level TodaySh

enan

doah

N

atl.

Park

Himalayas

How Are Really Big Mountains Built?

Orogeny in the Himalayas

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Continental Lithosphere

Will NOT Flush Down Subduction

Zones

Orogeny Folds Rocks

Review: New Lithosphere (Crust + Upper Mantle) is

Created at Spread Centers, Consumed at Subduction Zones

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What About Offsets in Spread Centers?

Transform Faults & Fracture Zones

Transform Faults

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San Andreas Fault:Right-Lateral

Transform Fault

Left-Lateral Offset!!Why?: Fault is

Produced by Offset, vs. Offset Produced by Fault

Plate Margins:

• Spread Centers (Mid-Ocean Ridges)• Subduction Zones (Trenches)• Transform Faults

Plate Margins:

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The Plates: Atlantic-Centered View

The Plates: Pacific-Centered View(Distorted by Mercator Map Projection)

What Drives Plate Tectonics?

1. Convection Cells in Mantle 2. Sinking of Cool, Dense Plates3. Mantle Plumes - Hot Spots

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Convection Cells

Convection Cells in MantleConvection Cells in Mantle

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Mantle Plumes

Mantle Plumes Under Continents

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• Known “Hot Spots”

Hawaiian Islands

Mantle Plumes - Hot Spots

•

Numbers = Age of Rockin Millions

of Years

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Sinking of Cool, Dense Plates

Seamount

Volcanoes Surrounded by Fringing Coral Reefs

NASA

Atolls: Submerged Volcanos Support ReefsOnly in Warm Clear Seas

Tuamoto Islands

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Continental Accretion

• The Craton: The Old Core of the Continent

• Mostly Exposed in the CnanadianShield

Craton

Craton

Plate Tectonic Evolution of Eastern North America

• Suspect Terranes

Accreted or “Suspect”Terranes in Western

USA, Canada

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History of “Suspect” Terrane

Accretion in Western North

America

Plate Tectonic Evolution of North America:

Accretion of Terranes

• suspect terranes (AK)

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Source:http://vishnu.glg.nau.

edu/rcb/

WVU

WVU


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WVU


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Taconic OrogenyContinent-Arc Collision

WVU

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Orogeny: Eastern N. Amer.

“Mirror” Image of West Coast


edu/rcb/

Taconic Orogeny

WVU


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Acadian OrogenyContinent-”Terrane” Collision

WVU


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Acadian Orogeny

WVU


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Alleghenian OrogenyContinent-Continent Collision

WVU

Allegehenian Orogeny Folded Appalachian Rocks

“Mirror” Image of West Coast

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edu/rcb/Penn.jpg

Pangaea = Gondwanaland +

Laurasia


edu/rcb/

Alleghenian Orogeny

WVU


edu/rcb/Perm.jpg

Pangaea = Gondwanaland

+ Laurasia

Ice Sheet

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Erosion and Isostatic Uplift of the Appalachians Since End of AlleghenianOrogeny

Laurasia

Gondwanaland

Source: http://vishnu.glg.nau.edu/rcb/160_1st.jpg

WVU


edu/rcb/ WVU

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Gondwanaland: Antarctica, South America, Africa,

Australia and India

Laurasia: North America, Europe,

most of Asia

Source:http://vishnu.glg.nau.edu/rcb/Jur.jpg


edu/rcb/ WVU

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edu/rcb/ WVU


edu/rcb/WVU

plate tectonics geol 101 lecture 24pages.geo.wvu.edu/~kite/geol101_2006lect24platetectiii.pdf ·...

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